Piston-ring construction



March 10, 1959 HSlA-Sl PlEN 2,877,072

PISTON-RING CONSTRUCTION Filed Sept. 13, 1956 INVENTOR.

HSlA-Sl PI N PISTON-RING CONSTRUCTION l-lsia-Si Pien, Waltham, Mass.,assignor to Willrening llglalnufacturing Co., Philadelphia, Pa., acorporation of e aware Original application January 22, 1954, Serial No.405,565,

2 Claims. (Cl. 309-44) The present invention relates to certain new anduseful 3-piece piston-rings for internal combustion engines and the likeand to a novel spacer-and-expander for such type piston-rings.

There has been a long-felt need for non-bottoming, self-expandingpiston-rings, namely piston-rings which exert an expansive forceirrespective of whether or not the piston-ring is in contactwitl'r thebottom of the ringreceiving groove, and which effect a uniformcircumferential engagement of the piston-ring sealers or rails againstthe cylinder walls.

- Recently a number of such non-bottoming circumferentially expansiblepiston-rings have been developed which have achieved a more or lesssatisfactory level of performance. However by and large suchself-expanding pistonrings have been of relatively complex constructionand have required a large amount of bending and milling in theirfabrication. Moreover, due to their structural complexity suchheretofore developed piston-rings have in some instances developed poorperformance characteristics after a period of use, with thespacer-and-expander portion of the piston-ring becoming deformed andcausing malfunction.

This invention has as an object the provision of a nonbottomingcircumferentially expausible piston-ring which does not require anysupport and is capable of functioning for greatly protracted periods ina highly satisfactory manner.

Another object of the present invention is a piston-ring which willconform to the cylinder-wall notwithstanding any slight out-of-roundnessor out-of-cylindrical shape of the cylinder-wall due either todistortion of the cylinderwall or due to wear, and one which will breakin readily.

Another object of the present invention is a piston-ring which will bearagainst the cylinder-wall with uniform or equalized outward radialpressure and which will eifectively seal against the cylinder-wall andwhich may have a relatively high unit of contact-pressure per unit ofcontact-area with the cylinder-wall, and which will provide adequatelubrication with good oil control.

For the purpose of illustrating the invention, there are shown in theaccompanying drawings one form thereof, although it is to be understoodthat the various instrumentalities of which the invention consists canbe various- 1y arranged and organized and that the invention is notlimited to the precise arrangements and organizations of theinstrumentalities as herein shown and described.

In the accompanying drawings in which like reference characters indicatelike parts:

Figure 1 is an exploded perspective view of a composite 3-piecepiston-ring representing one embodiment of the present invention.

Figure 2 represents a side sectional view of the same, in position inthe ring-receiving groove of a piston, with the sealing-rings of thepiston-ring contactng the cylinderwall.

Figure 3 is a plan view of a fragmentary portion of a cut strip of bandor ribbon of flat spring metal, such as Un rc d t s P ti tf 2,877,072Patented Mar. .10, 9

ICE

spring-steel, from which the spacer-and-expander of the three-piecepiston-ring of the present invention is formed, showing the first stagein the formation of the spacer-and expander. 7

Referring to Figures 1 and 2 for one embodiment of the piston-ring ofthe present invention, the piston-ring shown therein comprises an upperor top thin fiat sealing-ring, oil-scraper or oil-control ring element20, a bottom or lower sealing-ring, oil-scraper or oil-control ringelement 21, and a spacer-and-expander designated 66, comprising acontinuous radially corrugated circumferentially cornpre'ssible'andexpansible ring'having its ends 72 abutting each other when thespacer-and-expander is operatively positioned. The operative position ofthe spacer-and expanderis shown in Figure 1 where ends 77 are abutting.

The spacer-and-expander 66 comprises an axially and radially corrugatedfiat band of spring metal having spacer tabs 68 and rail-engaging tabs70, the latter being axial extensions of the radial innermost portions69 of spacer-and-expander 66. In the embodiment shown in the drawings,three spacer tabs 68 are provided intermediate each two rail-engagingtabs 70. Spacer tabs 68 project axially outwardly from the body ofspacer-and-ex pander 66 for a smaller distance than rail-engaging tabs70. As seen in Figure l, a spacer tab 68 is provided at the radiallyoutward extremity of each of the radial corrugation, with a spacertab'68 intermediate said radiallyoutwardly disposed spacer tab andtherail-engaging tab 70; with the outer axial surface or end 73 of eachspacer tab 68 serving as a seating surface for rails 20 and 21.

The free ends 72 of spacer-and-expander 66 abut when spacer-and-expander66 is operatively positioned (as shown in Figure 1).

The spaces between adjacent the tabs 68 and 70 pro vide oil passageways.If desired, the spacer-and-expander 66 may be slotted or perforated byaxially spaced slots or holes to provide additional oil passageways.

The spacer-and-expander 66 is milled or punched from a flat band (seeFigure 3) to form the rail-engaging tongues or tabs 70 positioned atregularly spaced intervals on both margins, with a plurality (in theembodiment shown, three) of spacer tabs 68 therebetween, and is thenradially corrugated and convoluted to form a finishedspacer-andexpander.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof, and it istherefore desired that the present embodiment be considered in allrespects as illustrative and not restrictive, reference being had to theappended claims rather than to the foregoing description to indicate thescope of the invention.

Having described the invention, the following is claimed:

1. A composite 3-piece non-bottoming piston-ring adapted to be confinedwithin the ring-receiving groove of a piston comprising a pair ofparallel-spaced sealingrings adapted to be disposed closely adjacent thesidewalls of said ring-receiving groove, a non-bottomingradially-corrugated circumferentially-expanding springmetalspacer-and-expander disposed between said pair of sealing-rings with itsends abutting each other and with such abutment causing thespacer-and-expander to resist circumferential compression whencompressed by the sealing rings when mounted in the cylinder, saidspacerand-expander comprising a radially corrugated band, a plurality ofradially-outwardly disposed sealing-ring seat ing tabs on and extendingaxially from each of the two opposite edges of each of saidcorrugations, with the axially outermost surface of said seating tabscomprising supporting surfaces on which the sealing-rings are seated andconstituting the sole axial spacing means between said asrao a sealingrings, said plurality of seating tabs providing axial support for saidsealing-ring both along a zone near the outermost periphery thereof aswell as along a zone spaced substantially inwardly from saidfirst-mentioned zone, radially-thrusting ring-engaging tabs on theradially innermost portion of said 'spacer-and-expander having greateraxial length than said seating tabs, the radially-outward surface ofsaid radailly thrusting ring-engaging tabs overlapping and engaging theinner peripheral edges of the sealing-rings, said sealing-rings andspacer-and expander being so constructed and arranged that when thesealin rings are collapsed to cylinder diameter and confined within theside-walls of said ring-receiving groove with the spacer-and-expanderdisposed between them and the aforesaid radially thrusting rin -engagingtabs engaged with the inner peripheral edges of said sealing-rings, thespacer-and-expa'nder will be compressed circumferentially and will urgethe sealing-rings outwardly by means of the aforesaid ring-engagingsurfaces of said radially-thrusting ring-engaging tabs.

2. A composite 3-piece non-bottoming piston-ring adapted to be confinedwithin the ring-receiving groove of a piston comprising a pair ofparallel-spaced sealingrings adapted to be disposed closely adjacent thesidewalls of said ring-receiving groove, a non-bottomingradially-corrugated circumferentially-expanding springmetalspacer-and-expander disposed between said pair of sealing-rings with itsends abutting each other and with such abutment causing thespacer-and-expander to resist circumferential compression whencompressed by the sealing rings when mounted in the cylinder, saidspacerand-expander comprising a radially corrugated band havingradially-outwardly disposed sealing-ring-seating and supporting tabs onwhich the sealing-rings are seated axially and constituting the soleaxial spacing means between said sealing rings, and providing axialseating and support for said sealing-rings. both in a zone near theoutermost periphery thereof as well as in a zone near the innerperiphery thereof, radially-thrusting ling-engaging tabs on the radiallyinnermost portion of said spacer-andexpander having greater axial lengththan said seating tabs, the radially-outward surface of saidradially-thrusting ring-engaging tabs overlapping and engaging the innerperipheral edges of the sealing-rings, oil-passageways for removing oilthrough said piston-ring, said sealingn iugs and spaCenand-expanderbeing so constructed arid; arranged that when the sealing-rings arecollapsed to cylinder diameter and confined; Within. the side-walls ofsaid ring-receiving groove with the spacer-and-expander disposed betweenthem and the aforesaid radiallyathrusting snga tabs. sns 's wit h n 'p rtzhsra edges of said sealing-rings, the spacer-and-expander will becompressed circumferentially and will urge thesealingrings outwardly bymeans of the aforesaid surfaces of said rings, outwardly by means of theaforesaid ring-engaging surfaces of saidradially-thrusting ring-engagingtabs.

References Cited in the file of this patent UNITED STA'IfES PATENTS2,229,578 Malpas Ian. 21 1241 2,297,104 Johnson Sept. 29, 1 9422,302,959 Johnson Nov. 24, 1 942 2,656,230 Phillips Oct. 20, 19532,744,803 Marien May 8, 195,6

